Many device manufacturing processes are performed in process chambers such as plasma etch chambers, plasma deposition chambers, thermal processing chambers, chemical vapor deposition chambers, atomic layer deposition chambers, etc. Processing of a substrate in a process chamber can lead to formation of material deposits on chamber components that are exposed to the process environment. The material deposits can be detrimental to device manufacturing and can require periodic wet or dry cleaning of the process chamber to remove the material deposits.
Chamber components are commonly replaced or cleaned after material deposits threaten particle problems, between incompatible processes to be run in sequence, and after detrimental processing conditions or poor processing results are observed. As device geometries have shrunk and tolerances on particle sizes and particle levels in process chambers and on processed substrates have been tightened, the frequency of chamber cleaning processes has increased, thereby lowering the throughput of the processing tool and increasing the cost of ownership.
Material deposits containing films with high film stress can require more frequent chamber cleaning in order to reduce particle levels in the process chamber. High film stress can promote film cracking when the total film thickness reaches a critical value and when the film undergoes thermal changes. Stress buildup can cause film flaking and breakup of the film into small particles that are transported throughout the process chamber. When particle detection techniques identify critical particle levels in a process chamber or on a processed substrate, a chamber cleaning process is used to restore proper manufacturing conditions.
Shrinking device geometries have also required a reduction in the thermal budget for various processing steps performed during device manufacturing. For example, thin silicon nitride (SiN) films that can be used as antireflective coatings (ARC), diffusion barriers, and protective cap layers have commonly been formed on a substrate in a low-pressure chemical vapor deposition (LPCVD) process by thermally reacting dichlorosilane (DCS, SiH2Cl2) and ammonia (NH3) at a substrate temperature of about 750° C., or higher. High processing temperatures, however, can be detrimental to the device. The processing temperature for forming SiN films on a substrate can be lowered to about 550° C. by thermally cracking an organic precursor such as bis-tertiary-butylamino-silane (BTBAS, SiH2(NHBut)2,) in the presence of NH3. However, the use of a BTBAS-based process instead of DCS and NH3 can result in increased particle levels in the process chamber and on a processed substrate due to significantly higher film stress and reduced adhesion of the SiN films to the chamber components. Based on the total SiN film thickness on chamber components, the time between required chamber cleaning processes can be an order of magnitude shorter when using a BTBAS-based process compared to using DCS and NH3.